The purpose of the administrative and clinical chemistry core is to provide overall daily administrative guidance for the project and laboratory support for the myriad of biochemical analyses proposed under the umbrella of this program project grant. By performing these determinations in a core laboratory setting, we will attain cost-effective utilization of the supplies and laboratory personnel required for this proposal. More importantly, it will insure quality control over the performance of these analyses and minimize the potential variation that might occur between several laboratories performing their own testing protocols. All of the urinary analyses will be performed in the Mineral Metabolism laboratory, a CLIA-approved laboratory. The procedures are all standardized and appropriate quality control specimens are included with each run. The analyses to be performed in this laboratory will subserve each component as specified in Table A. Components I, II, IV, and V will require 24-hour urine analyses for stone-risk parameters. Similar testing will also be accomplished on 2-hour fasting specimens as part of Components I and II. Titratable acidities will be a major need for component II and a minor part of component IV. Serum assays will require the use of both ELISA and radioisotopic methods. These assays will be performed in the RIA laboratory under the direction of Dr. Zerwekh. Except for the vitamin D metabolite analyses, all of the proposed tests are performed with commercially available kits and are currently employed assays in this laboratory. Component III will require a limited electrolyte assessment on rat urine and plasma. Three of the assays specific to component II, namely serum insulin, free fatty acid, and lactate will be performed in the laboratory of Dr. Nicola Abate, co-investigator for Component II.